Purification of Oil Field Production Water for Beneficial Use

ABSTRACT

A method for generating new water with attached water rights comprising identifying a source of production water and treating the water in appropriate ways to provide water appropriate for beneficial use such as agriculture, irrigation, industrial or municipal or potable applications. Appropriate permits are obtained to create the new water with attached water rights.

This application claims priority pursuant to 35 U.S.C. § 120 to and is acontinuation application of U.S. patent application Ser. No. 11/784,569filed 6 Apr. 2007 (the '569 application), which claimed the benefitpursuant to 35 U.S.C. § 119(e) of U.S. provisional patent applicationNo. 60/789,846 filed 6 Apr. 2006 (the '846 application). The '569 and'846 applications are each hereby incorporated by reference in theirentirety as though fully set forth herein.

I. FIELD OF THE INVENTION

This invention relates to a system and method for simply andeconomically producing agricultural augmentation water or potable waterfrom oil production water. In particular, the invention relates to asystem and process for microfiltration of production water so that itcan be used beneficially, rather than being reinjected into thegeological formation.

II. BACKGROUND OF THE INVENTION

Current water demands have prompted the investigation of alternativewater sources and ways to augment current water supplies. It has beensaid that, “Nothing in the future will have a greater impact on ourability to sustain our way of life and preserve our environment forfuture generations than water.” (The Statewide Water Supply Initiative,Colorado Department of Natural Resources.). These concerns transcendColorado and the Western United States and apply to the world resourceoutlook in general.

One potential source of augmentation water is the water included inhydrocarbons extracted from geological formations containing oil andnatural gas. The water included with the oil and/or gas produced fromthe well is termed “produced water” or “production water.” Prior to thisinvention, production water had not been considered a potential sourceof augmentation water. Indeed, it was a difficult and expensive taskjust to make production water suitable for disposal.

Typically production water is separated from the hydrocarbons using an“API” oil water separator. The principle of the API separator is toallow for the non-aqueous phase liquids (primarily the organics whichare lighter than water) to float to the surface. Then the organics areremoved from the production water and concentrated through the use of aheat treatment unit, which drives off the remaining water throughevaporation.

The API separator will recover the majority of the oil, but dissolvedmaterials and volatile organics will remain in the aqueous segment.Thus, production water usually contains high concentrations ofhydrocarbons and other inorganic constituents. Typically productionwater is disposed of by being re-injected under pressure back into thegeologic formation, through a Class II injection well, permitted by theUS EPA. Because of the contaminants in the production water, injectioninto other geological formations that can be used for a drinking watersource or into surface water is usually prohibited. In addition,re-injection is costly because it requires substantial pressure (and,therefore energy) to overcome the resistance within the geologicalformation. The Department of Energy estimates that 30 to 40 percent ofthe energy obtained from the formation as oil is used to re-inject ormove this water. (DOE—Sandia Conference, Salt Lake City, January 2006.)In addition, re-injection of production water into the formation dilutessubsequently-produced oil, adding additional costs to the recovery andprocessing of those hydrocarbons. Nevertheless, prior to the presentinvention, re-injection was the most straightforward method to disposeof production water, since it was quite difficult and costly to cleanthe production water sufficiently for direct discharge. “Directdischarge” is a term of art connoting discharge directly through a pipeto the surface water course or stream.

Thus, an efficient and effective treatment for upgrading productionwater would be beneficial both in providing high-quality water that canbe used in various water conservation schemes and in avoiding the costsand other detriments of re-injecting the production water under ground.

As used herein “production water” means water separated from theproduction stream of oil and gas wells. An example of the constituentsin a sample of production water from Wellington, Colo.—after APIseparation—is shown in Table 1

TABLE 1 Produced Water Quality Parameters After the Oil/Water SeparationProcess Typical Range of Values mg/l Inorganics Total Dissolved Solids(TDS) 1200 6000 Total Hardness as CaCO3 30 300 Total Alkalinity as CaCO31000 4000 Chloride (Cl) 40 1000 Fluoride <1 10 Phosphate (PO4) <0.5 30Nitrite + Nitrate − Nitrogen <0.5 40 (NO2 + NO3 − N)* Metals Antimony(Sb) <0.005 1.00 Arsenic (As)* <0.005 1.00 Barium (Ba)* 3.00 30.00Berylium (Be) <0.0005 1.00 Boron (B) 1.00 10.00 Cadmium (Cd) <0.001 1.00Chromium (Cr) <0.02 1.00 Copper (Cu) <0.01 1.00 Iron (Fe)* 0.10 30.00Lead (Pb) <0.005 5.00 Manganese (Mn)* <0.005 10.00 Mercury (Hg) <0.00020.10 Nickel (Ni)* <0.05 10.00 Selenium (Se) <0.005 5.00 Silver (Ag)<0.01 5.00 Thallium (Tl)* <0.002 1.00 Zinc (Zn) <0.005 10.00 OrganicsOil and grease* 20.0 200.00 Benzene* 1.00 10.00 Toluene* 1.00 5.00Ethylbenzene* 0.10 1.00 Xylenes, total* 1.00 5.00 n-Butylbenzene* 0.010.50 sec-Butylbenzene* 0.01 0.10 tert-Butylbenzene* 0.01 0.10Isopropylbenzene* 0.01 0.10 4-Isopropyltoluene* 0.01 0.10 Naphthalene*0.01 0.10 n-Propylbenzene* 0.01 0.10 1,2,4-Trimethylbenzene* 0.10 1.001,3,5-Trimethylbenzene* 0.10 1.00 Bromoform* <0.001 1.00This production water also contains paraffins and asphaltenes in anunmeasured, but not insignificant, amount.

Production water contains both inorganic and organic constituents thatlimit the discharge options available to the producer. Produced watercontains a range of constituents including dispersed oil, dissolved orsoluble organics, produced solids, scales (e.g., precipitated solids,gypsum (CaSO₄), barite (BaSO₄)), bacteria, metals, low pH, sulfates,naturally occurring radioactive materials (NORM), and chemicals addedduring extraction (Veil, et al., 2004). The oil related compoundsinclude benzene, xylene, ethyl benzene, toluene, and other compounds ofthe type identified in the sample analysis shown in Table 1 and in othercrude oil and natural gas sources. Normally, the production water willalso contain metals, e.g., arsenic, barium, iron, sodium and othermultivalent ions, which appear in many geological formations.

In order to produce a higher grade of water, for example, either“agricultural” or “augmentation” water, both the hydrocarbon componentsand heavy metals need to be removed. As used herein, “agriculturalwater” means water that will meet the basic standards dictated by theEPA or state agency as the primary agency for water quality in surfacewaters. “Potable water” means water that meets the primary and secondarydrinking water standards as defined by 40 CFR Sec.136.

As used herein “augmentation water” means water that can be used toaugment a water source, i.e., agricultural, industrial, municipal,irrigation or potable water. In a more restrictive sense it also meanswater that is supplied to keep a stream whole. In the nomenclature usedfor water rights in the Western portion of the United States“augmentation water” means water that protects individuals or waterusers that have a prior appropriation for the use of that water. A wateraugmentation plan is a procedure for replacing water to a stream systemwhose flows are depleted by the consumption of water, where the wateruser does not have a right to the water consumed. Consumption or“consumptive use” means the water has been placed in theevapo-transpiration cycle or otherwise not returned to the streamsystem. According to current ground water laws in the west with priorappropriation, if water under the land would reach a stream systemwithin approximately 100 years, it is deemed to be “tributary” to thatstream system; it supports the stream's flow. Other users may haverights to the stream flow; therefore, a new user cannot consume thewater unless the new user has a “water right” (decreed by a Water Courtor by a State Engineer) which allows their use of the water. Otherwise,a downstream user with senior water rights could be damaged because hemight not have enough water for his purpose. So, absent a water right,the new user must figure out a way to replace or “augment” his water useso the existing stream flow remains the same as before he used it.Augmentation may be made by purchasing water rights on the affectedstream system or by physically replacing the water used from anotherlegal water source. An augmentation plan is submitted to the Water Courtor State Engineer which governs the particular drainage basin in whichthe affected stream system lies. If the Court or State Engineer approvesthe plan, it will issue a decree which grants the use of the “tributary”water, provided that ongoing augmentation (replacement of used water) ofthat use occurs per the plan that is used by junior appropriators toobtain water supplies through terms and conditions approved by a watercourt that protect senior water rights from the depletions caused by thenew diversions, under the Prior Appropriation Doctrine. Typically thiswill involve storing junior water when in priority and releasing thatwater when a call comes on; purchasing stored waters from federalentities or others to release when a river call comes on; or purchasingsenior irrigation water rights and changing the use of those rights tooff-set the new user's injury to the stream. These plans can be verycomplex and it is suggested that an engineering consultant be retainedto allow for proper consideration of all hydrologic and water rightfactors.

Prior art methods of cleaning and upgrading production water have beenineffective and/or overly expensive. These methods include:

-   -   Oil Water Separation (API method): The normal method for oil        water separation is the use of an API oil water separator. The        principal of the API separator is to allow for the non-aqueous        phase liquids (“NAPL's”) to float to the surface. Then the        organics or NAPL's are removed from the production water and        concentrated through the use of a heat treatment unit. The oil        water separator will recover a majority of the oils, but any        dissolved materials in the remaining production water will not        be removed by the API unit. Thus, the method is useful in        recovering incremental amounts of oil from the production water,        but is ineffective in removing other contaminants from the        production water.    -   Precipitation: Precipitation is used for the removal of both        dissolved oils and heavy metals. The precipitation will react        with the dissolved oil and then flocculate and precipitate the        oil into a particle. This particle can then be removed through        floatation and filtration, i.e., the coagulant entraps both the        metal and oil particles and makes them “bigger” so they can        either float or be filtered from the solution. In some        instances, it has been suggested to further clean the effluent        from the precipitation stage by reverse osmosis. However,        precipitation and filtration is still ineffective in removing        volatile organic compounds, such as benzene. Further, processing        would be required to remove those organic compounds.    -   Adsorption: Activated carbon adsorption has been used for many        years as a method for the removal of dissolved organics.        Activated carbon will remove organics typically below method        detection limits listed in 40 CFR 136. However, this technology        is very expensive, and it does not normally remove heavy metals.    -   Nano Filtration: Nano filtration has been used for the removal        of sulfate ions in the field and has been shown to be very        effective. However, this would require microfiltration and        activated carbon for organic removal.    -   Organo-thiol ligands: The use of organo-thiol ligands has proved        very promising in the removal of specific toxic heavy metals and        dissolved organics from wastewater. However, they are very        expensive and work on a limited number of metal ions.    -   SMZ Removal—Application of “surfactant modified zeolites” is        also a technique utilized on produced waters for the removal of        benzene, toluene, ethylbenzene, and xylene, i.e., “BTEX,” and        other volatile organics. The technique is most effective on        benzene but is also effective on other organics. This technology        does not remove heavy metals, unless they are associated with        the organics being removed.

These prior art processes are all limited to certain aspects of cleaningup production water and do not present a comprehensive solution forupgrading production water to agricultural grade or potable water.Methods that have attempted to achieve that result comprise expensivemultiple step processes that sequentially and separately attempt toaddress each problem in cleaning up production water. Thus, for example,one process of cleaning up production water included separate steps for:warm softening; coconut shell filtration; cooling (fin-fan); tricklingfiltration; pressure filtration; ion-exchange; and reverse osmosis. (R.Funston et al., “Evaluation of Technical and Economic Feasibility ofTreating Oilfield Produced Water to Create a ‘New’ Water Resource,”(Ground Water Production Council Conference, Produced Waters Workshop,Colorado Springs, Colo., October 2002.)

Obviously, there is a need for a simple, economic process to producehigher grade water such as agricultural and/or potable water, from oiland gas production water.

Although the following description and example are focused on productionwater from oil and gas wells, it is anticipated that the invention mayalso have applicability to production water from gas wells, and othersimilar water-containing hydrocarbon materials, such as coal bed methanewater, obtained from geological formations.

III. SUMMARY OF THE INVENTION

The present invention provides both a method and system to produceagricultural grade or potable water from oil and gas production water.An important part of the process is the use of an appropriate ceramicfilter to facilitate separation of hydrocarbons and other contaminantsfrom the water. Appropriate pretreatment steps are used to assist in theinitial separation and to remove materials from the process stream thatwould cause particular problems in fouling the ceramic filter. The waterthat passes through the ceramic filter may be subjected to additionaltreatments to “finish” the water for the particular applicationintended.

In one embodiment of the present invention production water from an APIoil/water separator is treated by aeration and the aerated water is thensubjected to filtering in a standard walnut shell filtration unit. Thepre-treated water is then subjected to filtration with a ceramic filterto remove volatile organic compounds, e.g., benzene that may remain andshould be removed. Any residual benzene in the permeate can be removedutilizing activated carbon. Alternatively, the benzene may be removedusing surface modified zeolites of an appropriate mesh size, e.g., 14 to100 mesh.

Purified water from the ceramic microfiltration step can then bedischarged to the land surface as “agricultural water” or it can be sentto subsurface discharge. Because it has been purified, it need not beinjected into a subterranean oil and gas formation normally at a depthof 4,000 to 5,000 feet.

Alternatively the discharge from the ceramic microfilter can be furthertreated by activated carbon adsorption, reverse osmosis and/or ionexchange treatment for further purification. Indeed, water from theceramic filtration—and with or without one or more of these additionalprocesses—may be deemed “potable.”

IV. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be more readily described by reference to theaccompanying drawings in which:

FIG. 1 is diagram of one embodiment of the production water purificationprocess of the present invention.

FIG. 2 is a diagram illustrating one embodiment of a supplementalreverse osmosis purification procedure.

FIG. 3 is a diagram illustrating a typical engineering/legal process forestablishing design criteria for the beneficial water to be derived fromproduction water using the present invention.

V. DETAILED DESCRIPTION OF THE INVENTION AND A PREFERRED EMBODIMENT

One preferred embodiment of the present invention is depicted in FIG. 1(a process schematic) and the following description.

Oil field production fluids 2 recovered from a well 1 are subjected to aseparation process in a “knockout” tank or “API” separator unit 3 wherewater and oil separate under gravity conditions. Typical API unitsinclude water separation systems such as Envirex API Oil WaterSeparators available from US Filter Corporation recently acquired bySiemens AG and now known as “Siemens Water Technologies” headquarteredin Warrendale, Pa. In addition it is desirable to add a “reversebreaker” to the knockout tank to assist in the removal and separation ofemulsified oil. Appropriate “reverse breaker” compositions include ametal chloride, such as aluminum chloride, commercially available as“Petrolite” available from Baker Hughes Petroleum, Inc. in Sugar Land,Tex.

The oil overflow from the knockout tank is then processed through aheater treater unit (not depicted in FIG. 1) to improve the oil/waterseparation. The oil is stored in oil storage tanks for eventual sale.Usually, the water driven off in this process is vented to the air underpermit from the EPA.

These initial steps, including the use of the “reverse breaker,” areconventional procedures employed in the industry in removing water fromthe oil and gas recovered from the well. Typically the water withremaining oil and other contaminants is then reinjected into thegeological formation. Instead, the present invention can be used totreat this water so that it can be employed beneficially as agriculturalwater, drinking water or in a number of other uses, e.g., cooling waterfor power generation plants and other processes.

In the present invention, the water underflow from the knockout tank,i.e., the production water 4, then flows to an aeration tank 5. Theaeration process typically will have a large tank, with a hydraulicdetention time of at least 60 minutes, but preferably 3 hours. This willutilize a fine bubble diffuser to strip the well head gasses from theAPI unit. There is a gas/liquid ratio that is determined in thelaboratory for the best efficiency to achieve the desired water quality.The equipment is custom made. But the design of this equipment for thispurpose is readily known to one of ordinary skill in the art withoutundue experimentation. Among other things, the aeration process isintended to remove carbon dioxide and hydrogen sulfide. Aeration alsodrives off volatile organic compounds (“VOCS”) to the atmosphere,through a stripping process. The VOCs removed include the BTEXcompounds.

Theoretically, the aerated production water 6 could then be subjected tomicrofiltration. However, in many applications, the aerated productionwater still contains a number of contaminants—especially organiccompounds—that would rapidly impair the operation of the ceramic filterand would necessitate frequent cleaning with concomitant loss ofproduction. Accordingly, it is highly desirable to send the aeratedproduction water to a dissolved air flotation (“DAF”) tank and/ororganic filtration step to remove organics and any floating oils thatmight have been changed. This occurs because stripping of the VOCs,changes the organic contents, which change the overall reaction to thefilters—i.e., the parafins are soluble with the VOCs present, but whenthe VOCs are stripped, then the parafins come out of solution due to theaeration step. These processes are intended to remove any heavy fraction(e.g., paraffins and asphaltenes) to non-detectable levels prior toceramic microfiltration. If detectable amounts of paraffins andasphaltenes are included in the water treated by the ceramicmicrofilter, the ceramic microfilter will soon become fouled to thepoint of rendering that process inoperable. For example, in one test inwhich “walnut shell filtration” was not employed, the ceramicmicrofiltration process was rendered inoperable after only about fourweeks of operation. The removal of these heavy oil fractions allows theceramic filter to operate with acceptable run times (e.g., 2 to 3 days)between cleanings. This compares to run times of 12 to 20 hours withoutthis pretreatment.

Accordingly, one preferred form of filtration is the use of a “walnutshell filter 7,” to process aerated production water 6. The walnut shellfilter appears to be particularly affective in removing paraffins andasphaltenes. Suitable walnut shell filters are manufactured byHydroFlow, Inc. of Maumee, Ohio or US Filter. Walnut shell filtersnormally have an automatic backwash system based on head-loss across thefilter. A particularly suitable filter is the HydroFlow 125 availablefrom HydroFlow, Inc., Maumee, Ohio.

The walnut shell filter may be preceded by the DAF process. The DAF(dissolved air floatation unit) is sometimes used to remove anydissolved air that has been injected and any oil that might have comethrough the system. This also allows for any additional sediment tosettle out or float to the surface.

Also, it is possible to replace the DAF step by alternative designs. Forexample, if a DAF is not used, then a transfer pump can convey the waterthat passes through the walnut shell filter, i.e., filtered productionwater, 8 to a pretreatment tank or coagulant mix tank 9 where ironchloride coagulant can be added. The pH can be adjusted by the additionof caustic (NaOH), as required. In either case, the pretreated flow 10from the mix tank then passes to the concentration tank 11. The solution12 from the coagulation tank is subjected to crossflow ceramicmicrofiltration. If the iron chloride coagulant is employed, its use mayresult in the production of excess iron hydroxide solids, which wouldnecessitate periodic blowdown to a sludge storage tank for subsequentdewatering via filter press. This step is necessary, because the ironhydroxide sludge cannot be disposed underground where it would fill voidspaces and eventually clog the formation.

Generally, the process of the present invention will include either DAFor pretreatment and sludge filtration—but not both.

Waste from that DAF and the backwash water from the walnut shell filteris then sent to a Class II injection well for disposal. This backwashprovides the cleaning of the filter. The run times for the walnut shellfilter are typically 20 to 24 hours between backwashings.

The effluent 12 from the coagulation tank 11 is then subjected tocrossflow ceramic microfiltration (“CMF”) 13. Suitable membranematerials include titanium, alumina, and zirconium with a pore size of0.5 microns to 1.2 microns. The elemental membrane may have an averagepore size of 5 microns to 10 microns, although the average pore size ispreferably from 0.05 micron to 5 microns. Most preferred is a methodwherein the elemental membrane has an average pore size from 0.05 micronto 0.1 micron. The membranes are operated at pressures of 20 psi to 75psi.

Suitable CMF filters include alumina membranes with zirconia coatings0.01 micron pore size, 37 bore, 3.8 mm diameter, 1200 mm lengthavailable from ATECH Innovations, Gmbh, Gladbeck, Germany or US Filter.

Pretreated water 12 from the concentration tank 11 is fed into the feedport of the ceramic microfilter 13 modules where it passes tangentiallyover the membranes. The clean, filtered water permeates through themembranes and is collected in the shell of the module and removedthrough the permeate port. This filtered water is typically referred toas the “permeate” stream 14 and contains no or very low levels of oiland heavy metals. The solution that cannot permeate through the membraneflows down the length of the membranes, out the reject port, and backinto the concentration tank. This stream is commonly referred to as the“reject” or “concentrate” stream 15 and contains a suspension of metalhydroxides and particulates. A small amount of the reject stream istypically wasted to the solids bleed line and sent to the oil sale tankin order to prevent the feed stream from becoming too concentrated withsolids.

The inherent mechanical strength of the ceramic membranes allows for anon-line cleaning process, which is referred to as backpulsing.Backpulsing is a procedure by which a small amount of the permeate wateris forced backwards through the membrane into the feed stream. Thisdisplaces solids adsorbed onto the surface of the membrane. Since theprocess pump continues to run during the backpulse, any solids displacedfrom the membrane surface are swept back into the concentration tank.Successful backpulsing depends on a sharp, high-pressure pulse of thepermeate water backwards through the membrane. A separate“clean-in-place” (“CIP”) unit is provided for the periodic cleaning ofthe microfilters by serial treatment with acidic solution, basicsolution, an enzyme solution and a rinse. Suitable materials includesulfuric acid, sodium hydroxide, HOCl, and Ter-G-Zyme™ for routinecleanings. On occasion it may be necessary to use a heavy dutydegreasing “syrup,” i.e., BioSol™—MEGASOL to remove organic foulant(s),i.e., biological material(s) that are likely created in the aerationtank or walnut shell filter. Biosolve can remove this material and fullrecovery of the membranes is possible. BioSol™—MEGASOL is available fromEvergreen Solutions, Inc., Calgary, Alberta, Canada.

The permeate stream 14 is monitored for pH level and turbidity to ensurethat the oil and heavy metals are removed and the system is operatingproperly. A fluorescence meter is also used to monitor for organics andmicrobiological activity in the system. If any of the readings areimproper (based on process characteristics identified herein or theintended use of the beneficial water), the permeate water isre-circulated to the precipitation tank and an alarm occurs until thecondition is corrected. Bench mark readings for these processparameters, e.g., benzene, can be developed on site with laboratoryverification for discharge parameters. Therefore, typical settings forthese parameters will vary with each site and need to be field verified.This monitoring is within the skill of the art.

Non-hazardous waste from the ceramic microfiltration process is sent toa permitted land fill (not depicted on FIG. 1).

The process as described herein has focused on production water, i.e.,water typically separated from the fluids obtained from wells producingoil and gas. This production water includes a number of materials thatcan substantially foul the ceramic microfilter and interfere with itseconomical operation. In other applications, such as coal bed methane,the raw material does not contain some of these contaminants,particularly the heavier oil fractions such as paraffins andasphaltenes. In those circumstances, the aqueous feedstock may only needto be aerated before the aerated effluent is treated by ceramicmicrofiltration. Treatment in the walnut shell filter or by DAF is notrequired. The permeate from the CMF is then treated by reverse osmosisor electrodialysis reversal (“EDR”) to produce water having therequisite qualities for the intended beneficial purpose.

Depending on the particular production water involved and the beneficialuse in which the water may be employed, the purified effluent 14 fromthe ceramic microfiltration 13 may not require any further processing.However, it is more likely that one or more final clean-up stages may beuseful to achieve the highest beneficial use.

The highest beneficial use of this water is augmentation water for watersupplies. This can be done using the following process 301 as depictedin FIG. 3:

-   -   1. Once the production water source is identified, a geologic        investigation can be performed to determine the non-tributary        status of the water. FIG. 3, steps 302 and 303.    -   2. If interest is obtained FIG. 3, step 304, then the process        can proceed to obtain permits for this water including the well        permit from the state engineer, the discharge permit from the        water quality control agency and the permit to discharge this        water from the oil and gas commission. FIG. 3, step 304.    -   3. If the non-tributary status of this water can be verified,        then potential users of the purified water can be identified.        FIG. 3, step 305    -   4. Once the permits for discharge have been obtained, a facility        can be designed and built using the process features described        above. FIG. 3, steps 307 to 310.    -   5. A perpetual water right FIG. 3, step 306 can then be obtained        from the state where the water is located to allow for the        beneficial use of this water. FIG. 3, step 311        By performing the foregoing steps, it is possible to increase        the value of the purified water by at least 10 times its        original value.

In particular, it is anticipated that the permeate 14 from ceramicmicrofiltration 13 will be subjected to treatment with activated carbonin the contactor 16 to remove additional volatile organic compounds andto provide final filtration to produce purified water 17 for beneficialuse. As shown in FIG. 1, this water is sent to storage reservoir 18 andmay then be used for augmentation or another beneficial purpose.Suitable absorption units include pressure vessels (ASME vessels)available from US Filter. The empty bed contact time is typically 20 to30 minutes. The mesh size is 20 to 40 mesh. The activated carbon base istypically coconut shells, but will depend on the actual VOCs beingremoved.

Other forms of post-filtration treatment can be employed depending onthe quality of that water and the intended use. Additionalpost-treatment processes may be employed to further treat the waterprior to discharge. These include membrane separation by reverse osmosis(“RO”) and/or ion exchange (“IX”). The components that would be includedin the RO process include booster pumping, scale inhibition, pHadjustment (acid/base), membrane separation and CIP using formulatedcleaning agents. Components required for ion exchange include theexchange columns and regeneration using acid and base.

Acidic and basic wastes generated in the CIP of the CMS and the IXregeneration can be neutralized in tanks and then recycled through thefull treatment process. Enzymes and detergents used in CMS and RO CIPcan be collected and diverted to storage for eventual undergroundinjection through a Class II injection. It does not go back into theformation that hydrocarbons are extracted from, but another formation.As described herein, this stream and several other streams containingcontaminants may be re-injected back into the ground, but this is only asmall portion of the production water, and the re-injection of thiswater can be accomplished at a fraction of the cost of re-injecting allof production water back into the ground.

FIG. 2 provides an illustration of the beneficial use of the purifiedproduction water. The production water, as mentioned in FIG. 1, can beaugmentation water. This water is placed into a surface water orgroundwater to augment the current water supply. This water 202 can thenbe pumped from this shallow groundwater 201 and can be used for: (1)irrigation water 203 and/or (2) raw water 204 for a potable watertreatment plant 205. If option (1) is selected, then the water 203 isplaced on crops for agricultural purposes. If option (2) is selected,then the water 204 is placed into a holding tank 206 for flowequalization. The next step is a pre-filtration 207 to remove anyparticulates. Normally, a caterage filter 207 will be utilized that hasan effective removal of particles in the size of 1.0 microns or greater.This will remove any pathogens from the raw water. The next step is totreat the water for removal of any salts. This is accomplished through areverse osmosis system. Normally anti-scalants will be added to preventclogging of the RO membrane 208. In addition, normally about 10 percentof the flow bypasses 209 the RO membranes. The RO System 210 will removeall salts, which will also remove the taste of the water. Through thebypass 209, it is possible to keep some of the salts for a TDS ofapproximately 300 mg/l. This will impart a good taste to the finishedpotable water system 211. From this location, a disinfectant 212 may beadded to meet the USEPA standards for potable water. Some of the water213 is saved for periodic cleaning of the membranes. Thus, FIG. 2illustrates how purified production water, initially provided asaugmentation water, can be put to better use.

VI. EXAMPLE

A treatment facility was constructed using water from an oil well in theWellington field of Colorado. The test employed a typical API unit toprovide a rough separation of liquid hydrocarbons from the productionwater. The test employed the following parameters:

a. The effluent from the API unit flowed into a 2500 bbl aeration flowequalization tank.

b. From the aeration tank, the water flowed to a DAF system sized for250 gpm.

c. The water from the DAF flowed into the walnut shell filter for theremoval of asphaltines and parafins.

d. The next step is the chemical feed tank. The chemical addition offerric chloride was added to precipitate any heavy metals and emulsifiedoils within the system. The feed rate for the coagulation chemicalferric chloride varied between 80 to 120 mg/L. The chemical additiontank had a hydraulic retention time of 20 minutes.

e. From the chemical addition tank, the oil production water was pumpedto the ceramic membrane having a pore size of 0.1 micron. The normaloperating pressure of the CMF varied between 38 to 48 psi. This providedthe physical separation of purified water from the oil and othercontaminants including heavy metals.

e. The permeate from the ceramic membrane was then transferred to theactivated carbon filtration system for final VOC removal.

f. During this test, a back pulse system was employed to allow forlonger run times. This back pulse pushed the permeate water backwardsthrough the membrane to clean it. This was performed approximately every90 to 120 seconds. The backpulse pressure is normally between 400 to 500psi over a period of less than 0.1 seconds. This creates a water hammerphysically cleaning the membranes and allowing for longer run times.

Results demonstrated improved filter runs with reduced membrane fouling,and satisfactory reduction in VOC concentration, as shown in Table 2.

TABLE 2 W3 Produced water effluent quality (Stewart Environmental, 2004)Raw Water Treated Water Inorganics Total Dissolved Solids (TDS) 22922370 Total Suspended Solids (TSS) 10 <5 Nitrite + Nitrate − Nitrogen<0.5 0.9 (NO₂ + NO₃ − N) Metals Antimony (Sb) <0.005 <0.005 Arsenic (As)<0.005 <0.005 Barium (Ba) 9.26 0.063 Berylium (Be) <0.001 <0.00011 Boron(B) 2.76 2.42 Cadmium (Cd) <0.001 <0.001 Chromium (Cr) <0.02 <0.005Copper (Cu) <0.01 <0.01 Iron (Fe) 0.24 0.13 Lead (Pb) <0.005 <0.005Manganese (Mn) 0.031 0.040 Mercury (Hg) <0.0002 <0.0002 Nickel (Ni) 0.04<0.02 Selenium (Se) <0.005 <0.005 Silver (Ag) <0.01 <0.005 Thallium (Tl)<0.002 <0.002 Zinc (Zn) <0.005 0.052 Organics Oil and grease 42 <5Benzene 2.45 <0.001 Toluene 1.78 <0.010 Ethylbenzene 0.428 <0.010Xylenes, total 1.989 <0.010 n-Butylbenzene 0.043 <0.010 sec-Butylbenzene0.022 <0.010 tert-Butylbenzene 0.037 <0.010 Isopropylbenzene 0.065<0.010 4-Isopropyltoluene 0.033 <0.010 Naphthalene 0.134 <0.010n-Propylbenzene 0.076 <0.010 1,2,4-Trimethylbenzene 0.372 <0.0101,3,5-Trimethylbenzene 0.356 <0.010 Bromoform 0.480 <0.010 All resultsexpressed in mg/L

The foregoing invention has been described with respect to certainpreferred embodiments for use with oil and gas production water. It isanticipated that the general principles of the invention may be embodiedin other forms of operating systems without departing from the spirit ofthe invention.

1. A method for creating new rights for beneficial use of water, saidmethod comprising: identifying a production water source; treating aliquid obtained from the production water source that previously was notplaced to any beneficial use and had no rights associated withbeneficial use; and obtaining a beneficial use right in the productionwater based on an executed contract for end user beneficial use.
 2. Amethod according to claim 1, further comprising obtaining a right fromthe mineral operator or working mineral interest owner in the productionwater source.
 3. A method according to claim 1, further comprisingconducting a geological investigation to determine the non-tributary orfossil water status of the production water source.
 4. A methodaccording to claim 1, further comprising obtaining one or more dischargepermits for point source discharges to surface water or shallow groundwater.
 5. A method according to claim 1, further comprising obtainingapproval from a regulatory authority.
 6. A method according to claim 5,wherein the regulatory authority is a state oil and gas commission.
 7. Amethod according to claim 1, further comprising securing water rightsassociated with the point source discharge to facilitate beneficial useby augmentation or exchange.
 8. A method according to claim 1, furthercomprising using the production water directly for beneficial uses.
 9. Amethod according to claim 1, wherein the liquid is treated sufficientlyto render the liquid potable.
 10. A method according to claim 1, whereinthe liquid is treated using a filtration process.
 11. The method ofclaim 10, wherein the filtration process comprises ceramicmicrofiltration.
 12. The method of claim 10, wherein the treatmentfurther comprises a process selected from the group consisting of:activated carbon treatment; membrane separation by reverse osmosis; ionexchange chromatography; or pH adjustment.
 13. A method according toclaim 10, wherein the liquid is subjected to post-filtration treatment.14. A method of generating new water with attached water rights, themethod comprising: obtaining a liquid mineral mixture from anon-tributary source, the liquid having rights attached thereto andowned by a first party; processing the liquid mineral mixture to yieldliquid waste product including at least a water component and ahydrocarbon component; processing the liquid waste product to separateat least portions of the hydrocarbon component to produce a separatedwater component having a higher water quality grade than the liquidwaste product; obtaining evidence in a tangible medium of a transfer ofrights in the liquid waste product to a second party; and obtainingevidence in a tangible medium of a conversion of the rights in theliquid waste product to beneficial use rights in the separated watercomponent owned by the second party and based on evidence in a tangiblemedium of assignment of beneficial use interest in the separated watercomponent to that second party.
 15. A method according to claim 14,further comprising: removing volatile hydrocarbons, paraffins andasphaltines from the liquid waste product to create pretreatedproduction water; and subjecting the pretreated production water tofiltration using a ceramic microfilter to produce the permeate water forbeneficial use, whereby the removal of the volatile hydrocarbons,paraffins and asphaltines is effective to a sufficient extent to enablethe ceramic microfilter to operate continuously except for routinecleaning and backwashing.
 16. A method according to claim 15, whereinthe removing of volatile hydrocarbons, paraffins and asphaltinesincludes treating the liquid waste product with a walnut shell filter.17. A method according to claim 15, wherein the removing of volatilehydrocarbons paraffins and asphaltines includes aerating the liquidwaste product to produce an aerated production water and then treatingthe aerated production water with a walnut shell filter.
 18. A methodaccording to claim 15, wherein the permeate water is treated withactivated charcoal.
 19. A method according to claim 18, wherein thewater passing through the activated charcoal is further treated by aprocess selected from the group consisting of reverse osmosis and ionexchange.
 20. A method according to claim 15, wherein the filtrationwith a ceramic microfilter is conducted at a pressure of approximately20 psi to 75 psi.
 21. A method according to claim 15, wherein thefiltration using a ceramic microfilter is conducted using a filterconstructed of a material selected from the group consisting oftitanium, alumina, and zirconium having an average pore size of 5microns to 10 microns.
 22. A method according to claim 15, wherein thefiltration using a ceramic microfilter is conducted using a filterhaving an average pore size of 0.05 microns to 1 micron.
 23. A methodaccording to claim 15, wherein the pH of the production water isadjusted to remove iron by precipitation.
 24. A method according toclaim 14, wherein the liquid mineral mixture is further processed toproduce a separate mineral component.
 25. A method according to claim14, wherein the non-tributary nature of the water is determined by atleast one member of the group consisting of a state engineer and a WaterCourt.
 26. A method of generating new water with attached beneficial userights, comprising: identifying a source of production water; conductinga geological investigation for non-tributary water determination;obtaining a permit allowing beneficial use of the non-tributaryproduction water; obtaining water user approval for purchase or lease;securing water rights for a surface water source including anaugmentation plan and/or exchange using the non-tributary productionwater; designing a production water treatment plant to provide treatedproduction water; obtaining discharge permits for surface waterdischarge of the treated production water; obtaining any approvals froman oil and gas commission; constructing the production water treatmentfacility; treating the production water using the production watertreatment facility; and obtaining a right in the treated productionwater based on an executed contract or other assignment so thatbeneficial use rights may be leased or sold.
 27. The method of claim 26wherein the processing of production water comprises a step ofmicrofiltration.